表單中的第一個參數不能包含零或爲空（acts_as_commentable錯誤）

Question

所以我試圖讓我的應用程序中的acts_as_commentable_with_threading gem工作。我想允許用戶評論特定事件（events/show.html）。我認爲我沒有正確設置它，因爲我得到了下面的錯誤。

錯誤：

顯示/Users/user/Sites/new_work/app/views/events/show.html.erb其中行＃36提出：

First argument in form cannot contain nil or be empty 


</div> 
<div class="name"></div> 
<div id="comments"> 
<%= form_for @comment do |f| %> <---- it's referring to this line 
<div><%= f.hidden_field :event_id, value: @event.id %></div> 
<div><%= f.text_field :body, row: 20, placeholder: "Leave a comment" %></div> 
<%= f.submit "Post Comment" %> 

comments_controller.rb

class CommentsController < ApplicationController 
    before_filter :load_commentable 

    def index 
    @comments = @commentable.current_user.comments 
    end 

    def new 
    @comment = @commentable.current_user.comments.new 
    end 

    def create 
    @comment = @commentable.current_user.comments.new(params[:comment]) 
    if @comment.save 
     redirect_to @commentable, notice: "Comment created." 
    else 
     render :new 
    end 
    end 

    private 

    def load_commentable 
    resource, id = request.path.split('/')[1, 2] 
    @commentable = resource.singularize.classify.constantize.find(id) 
    end 

end 

comment.rb SNIPPIT只

class Comment < ActiveRecord::Base 
    attr_accessible :title, :body, :subject 

    acts_as_nested_set :scope => [:commentable_id, :commentable_type] 

    validates :body, :presence => true 
    validates :user, :presence => true 

    # NOTE: install the acts_as_votable plugin if you                           
    # want user to vote on the quality of comments.                            
    #acts_as_votable                                    

    belongs_to :commentable, :polymorphic => true 

    # NOTE: Comments belong to a user                               
    belongs_to :user 

event.rb

class Event < ActiveRecord::Base 
    attr_accessible :title, :description, :location, :date, :time, :event_date 

    acts_as_commentable 
    has_many :comments, as: :commentable 
    belongs_to :user 

    after_create :update_event_date 

    def update_event_date 
    date = self.date.to_s 
    time = self.time 

    hour = Time.parse(time).strftime("%H:%M:%S").to_s 
    event_date = (date + ' ' + hour).to_time 
    self.update_attributes(event_date: event_date) 
    end 
end 

評論/ form.html.erb

<%= form_for [@commentable, @comment] do |f| %>                            
<% if @comment.errors.any? %>                                 
<div class="error_messages">                                 
    <h3>Please correct the following errors.</h3>                            
    <ul>                                       
    <% @comment.errors.full_messages.each do |msg| %>                           
    <li><%= msg %></li>                                  
    </ul>                                      
</div>                                       
<% end %>                                      
<div class="field">                                   
    <%= f.text_field :body, rows: 10, placeholder: "Leave a comment" %>                       
</div>                                       

<div class="actions">                                   
    <%= f.submit "Post comment", class: "btn" %>                             
</div>                                       
<% end %>    

events_controller.rb

class EventsController < ApplicationController 
    before_filter :authenticate_user! 

    def index 
    @user = current_user 
    @events = Event.all 
    end 

    def new 
    @event = Event.new 
    end 

    # def create                                     
    # @event = Event.new(params[:event])                              
    # if @event.save                                   
    #  redirect_to :action => 'index'                               
    # else                                      
    #  @events = Event.find(:all)                                
    #  render :action => 'new'                                
    # end                                      
    # end                                      

    def create 
    @event = current_user.events.new(event_params) 

    respond_to do |format| 
     if @event.save 
    format.html { redirect_to :back, notice: 'Event was successfully created.' } 
    format.json { render action: 'show', status: :created, location: @event } 
    format.js 
     else 
     format.html { render action: 'new' } 
    format.json { render json: @event.errors, status: :unprocessable_entity } 
    format.js 
     end 
    end 
end 

    def show 
    @event = Event.find(params[:id]) 
    end 

    def edit 
    @event = Event.find(params[:id]) 
    end 

    def update 
    @event = Event.find(params[:id]) 
    if @event.update_attributes(params[:event]) 
     flash[:success] = "Event updated." 
     redirect_to @event 
    else 
     render 'edit' 
    end 
    end 

    def destroy 
    @event = Event.find(params[:id]) 
    @event.destroy 

    respond_to do |format| 
     format.html {redirect_to :back} 
     format.js 
    end 
    end 

    private 
    # Use callbacks to share common setup or constraints between actions.                      
    def set_event 
    @event = Event.find(params[:id]) 
    end 

的routes.rb

New_app::Application.routes.draw do 

    # get 'auth/:provider/callback', to: 'sessions#create'                          
    # get 'auth/failure', to: redirect('/')                              

    root to: "home#landing" 

    devise_for :users, :controllers => {:registrations => "users/registrations", 
    :sessions => "users/sessions", 
    :passwords => "users/passwords", 
    :omniauth_callbacks => "users/omniauth_callbacks" 
    } 

    get "welcome", to: "home#welcome", as: 'welcome' 

    devise_scope :user do 
    # get "edit/edit_account", :to => "devise/registrations#edit_account", :as => "account_registration"              
    get 'edit/edit_account' => 'users/registrations#account_registration', as: :edit_account 
    end 

    # patch '/users/:id', to: 'users#update', as: 'user'                           
    get 'profile/:id' => "users#show", as: :profile 
    get 'disconnect' => 'users#disconnect' 

    resources :users do 
    resources :questions 
    end 
    resources :photos 

    resources :events do 
    resources :comments 
    end 

    post "/events/add_new_comment" => "events#add_new_comment", :as => "add_new_comment_to_events", :via => [:event] 

    resources :questions 
end 

徵求意見

event_comments GET  /events/:event_id/comments(.:format)   comments#index 
          POST  /events/:event_id/comments(.:format)   comments#create 
     new_event_comment GET  /events/:event_id/comments/new(.:format)  comments#new 
     edit_event_comment GET  /events/:event_id/comments/:id/edit(.:format) comments#edit 
      event_comment GET  /events/:event_id/comments/:id(.:format)  comments#show 
          PATCH /events/:event_id/comments/:id(.:format)  comments#update 
          PUT  /events/:event_id/comments/:id(.:format)  comments#update 
          DELETE /events/:event_id/comments/:id(.:format)  comments#destroy 

Answer 1

耙路線是在您的活動控制器的 「作秀」 行爲定義@comment？你也可以發佈事件控制器代碼嗎？

重複檢查的一件事是確保呈現show.html.erb視圖的操作具有已定義的@comment變量。您好像正在收到消息，因爲@comment變量爲

<%= form_for @comment do |f| %> 

當您呈現視圖時，它目前爲零。

在對事件的控制器中的「秀」的動作，試圖通過增加設置@comment變量：

@comment = @event.comments.new 

編輯2：請確保您已設置您的routes.rb文件來處理事件的評論，所以假設你使用RESTful路由，在你的routes.rb中就像下面這樣。如果你可以發佈路線文件，這也會有所幫助。

resources :events do 
    resources :comments 
end 

Answer 2

錯誤是應用程序/視圖/事件/ show.html。ERB這意味着你活動控制器的顯示動作@ply缺少@comment變量

def show 
    @event = Event.find(params[:id]) 
    @comment = ....what ever you need to pull in the comments.... 
    end